This invention relates generally to ammunition and more particularly to a unitary charge module for separate ammunition used in large caliber artillery.
Large caliber gun ammunition (such as is used on naval ships) does not normally have a single, unitary cartridge but instead typically includes two separate components: (a) a projectile and (b) one or more separate bags or containers of propellant. The projectile and the propellant containers are sequentially loaded into the breech of the gun either by hand or automatically. The effective range of the projectile can be selected by the choice of how many bags or containers of propellant are loaded into the gun.
Early separate propellant charge containers were typically bags of either silk or cotton which had pockets to contain the ignition charge at one end. Typical designs of such containers are described in U.S. Pat. Nos. 864,725; 1,329,503; 1,625,631; 2,405,104; and 3,771,460.
A more recent patent, U.S. Pat. No. 4,282,813 discloses a unitary propellant charge formed in a cylindrical shape having a central bore along its axis for propagating a primer flash. The charge contains a priming charge at one end and has an outer coating of a heat shrinkable polyester film such as mylar. This unitary charge is not designed for use where multiple charges are employed.
Current propellant charge containers are made today so that they are interchangeable in terms of orientation. That is, they are axially symmetrical and radially symmetrical about the longitudinal axis so that several can be loaded and they can be loaded in the dark without danger of incorrect front to back orientation. Typical of such charge containers are those disclosed in U.S. Pats. 4,702,167, 4,864,932, and 4,922,823.
U.S. Pat. Nos. 4,702,167 and 4,864,932 also disclose a unitary propellant charge having a cylindrical shape with a central bore therethrough. However, in these patents, the charge, composed of black powder, surrounds a tubular igniter or a stack of self centering rings made of extruded porous nitrocellulose or an admixture of nitrocellulose and a known primer charge such as boron/potassium nitrate powder. The main charge of black powder is contained in an annular envelope which uses the igniter as the inner wall. This arrangement permits stacking without alignment problems and allows variation of the total propellant quantity by loading multiple charges in a gun.
U.S. Pat. No. 4,922,823 discloses an igniter charge for a unitary propellant charge module such as is disclosed in the last described patents in which the igniter is made of a composite of an inner igniter tube and an outer support tube. Both tubes are made of extruded propellant powders and may be separately pressed in a mold to form the tubes. The igniter and support tubes are then adhesively bonded together. Alternatively the two tubes may be coextruded together. The igniter charge is then assembled into an annular main charge container.
One problem with such separate ammunition charge modules using conventional propellants such as black powder or nitrocellulose based extruded propellant formulations such as JA2 and M30 is the high sensitivity of these propellants to shock and their high flame temperatures. This combination results in a relatively high vulnerability of these propellants to the effects of shape charge attack. In addition, the high flame temperatures severely limits the potential rate of cannon fire and barrel life.
It is therefore an object of the present invention to provide an improved unitary charge module of separate ammunition.
It is another object of the present invention to provide a unitary propellant charge module that has improved resistivity to shock impulses.
It is another object of the invention to provide an improved unitary propellant charge to extend barrel life of the gun in which the charge is fired.
It is another object of the invention to provide a unitary charge module of compacted spherical propellant grains.
It is another object of the invention to provide a unitary propellant charge having a center core igniter of compacted spherical propellant grains.
It is another object of the invention to provide a unitary propellant charge of compacted spherical propellant requiring no separate combustible case enclosing the charge.